title: Effectiveness of cross-linking posterior segmental instrumentation in adolescent idiopathic scoliosis: a 2-year follow-up comparative study.
abstract: BACKGROUND
  Surgeons continue to debate the need for a cross-link (CL) in posterior spinal instrumentation constructs with segmental pedicle screws in adolescent idiopathic scoliosis (AIS). Advantage of CLs is increased stiffness of the construct, and disadvantages include added expense and risk of late operative-site pain and pseudarthrosis.
  
  
  OBJECTIVE
  To compare the effectiveness of using CLs versus using no cross-links (NCLs) in posterior segmental instrumentation in AIS.
  
  
  METHODS
  Retrospective comparative study, level of evidence 3.
  
  
  METHODS
  Seventy-five AIS patients less than 21 years of age, who underwent posterior spinal instrumentation with segmental pedicle screws (25 with CLs and 50 with NCLs) at a single institution with 2-year follow-up, are described.
  
  
  METHODS
  Physiologic measures include imaging: thoracic and lumbar Cobb angles, correction rate, apical vertebral translation (AVT), and apical vertebral rotation (AVR); self-report measures include Scoliosis Research Society (SRS) domain outcome scores.
  
  
  METHODS
  Preoperative (pre-op) and postoperative first erect, 1-year, and 2-year follow-up radiographs were measured. Instrumentation-related complications and normalized SRS scores were recorded. Independent sample t test, χ(2) test, and repeated-measures analysis of variance were used for analyses.
  
  
  RESULTS
  The average age at surgery was 14 years, the mean pre-op Cobb angle was 57°, and the mean number of levels fused was 10.9. The groups were similar preoperatively with respect to age, sex, Lenke curve, Cobb angle, AVT, and Risser grade and were similar intraoperatively for levels fused and anchor density. There was no difference in AVR, Cobb angle, correction rate, or AVT between the groups (p>.05). Complications included one wound infection in the CL group and one painful scar in the NCL group. There were no differences in SRS domain scores.
  
  
  CONCLUSIONS
  We observed no differences in maintenance of correction, SRS scores, and complications with or without cross-linking posterior segmental instrumentation in AIS patients over 2-year follow-up. Further follow-up is necessary.
authors.affiliation: Department of Orthopedics, Nemours/Alfred I. duPont Hospital for Children, 1600 Rockland Rd, PO Box 269, Wilmington, DE 19899, USA.
authors.forename: Arjun A
authors.initials: AA
authors.lastname: Dhawale
authors.forename: Suken A
authors.initials: SA
authors.lastname: Shah
authors.forename: Petya
authors.initials: P
authors.lastname: Yorgova
authors.forename: Geraldine
authors.initials: G
authors.lastname: Neiss
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Layer
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rogers
authors.forename: Peter G
authors.initials: PG
authors.lastname: Gabos
authors.forename: Laurens
authors.initials: L
authors.lastname: Holmes
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D017060:Patient Satisfaction; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome
keywords: AIS; Cross-links; Pedicle screw; Posterior instrumentation; Transverse connectors